Thuban/UI/baserenderer.py

# Copyright (c) 2001, 2002, 2003 by Intevation GmbH
# Authors:
# Bernhard Herzog <[email protected]>
# Jonathan Coles <[email protected]>
# Frank Koormann <[email protected]>
#
# This program is free software under the GPL (>=v2)
# Read the file COPYING coming with Thuban for details.

"""Basic rendering logic for Thuban maps

The code in this module is completely independend of wx so that it can
be tested reasonably easily and it could make it easier to write non-wx
renderers.
"""

from __future__ import generators

__version__ = "$Revision$"
# $Source$
# $Id$

import sys
import traceback

from Thuban.Model.layer import Layer, RasterLayer
from Thuban.Model.data import SHAPETYPE_ARC, SHAPETYPE_POINT
from Thuban.Model.label import ALIGN_CENTER, ALIGN_TOP, ALIGN_BOTTOM, \
     ALIGN_LEFT, ALIGN_RIGHT

import Thuban.Model.resource

if Thuban.Model.resource.has_gdal_support():
    from gdalwarp import ProjectRasterFile


#
#       Renderer Extensions
#
# The renderer extensions provide a way to render layer types defined in
# Thuban extensions. The renderer extensions are stored as a list with
# (layer_class, draw_function) pairs. If the renderer has to draw a
# non-builtin layer type, i.e. a layer that is not a subclass of Layer
# or RasterLayer, it iterates through that list, tests whether the layer
# to be drawin is an instance of layer_class and if so calls
# draw_function with the renderer and the layer as arguments. Since
# drawing is done incrementally, the draw_function should return an
# iterable. The easiest way is to simply implement the draw_function as
# a generator and to yield in suitable places, or to return the empty
# tuple.
#
# New renderer extensions should be added with add_renderer_extension().
# If necessary the extensions list can be reset with
# init_renderer_extensions().

_renderer_extensions = []

def add_renderer_extension(layer_class, function):
    """Add a renderer extension for the layer class layer_class

    When an instance of layer_class is to be drawn by the renderer the
    renderer will call function with the renderer and the layer_class
    instance as arguments. Since drawing is done incrementally, the
    function should return an iterable. The easiest way is to simply
    implement the draw_function as a generator and to yield True in
    suitable places, or to return the empty tuple if it's not possible
    to do the rendering in incrementally.
    """
    _renderer_extensions.append((layer_class, function))

def init_renderer_extensions():
    """(Re)initialize the list of renderer extensions

    Calling this function outside of the test suite is probably not
    useful.
    """
    del _renderer_extensions[:]


#
#       Base Renderer
#

class BaseRenderer:

    """Basic Renderer Infrastructure for Thuban Maps

    This class can't be used directly to render because it doesn't know
    anything about real DCs such as how to create pens or brushes. That
    functionality has to be provided by derived classes. The reason for
    this is that it makes the BaseRenderer completely independend of wx
    and thus it's quite easy to write test cases for it.
    """
    # If true the render honors the visibility flag of the layers
    honor_visibility = 1

    # Transparent brushes and pens. Derived classes should define these
    # as appropriate.
    TRANSPARENT_PEN = None
    TRANSPARENT_BRUSH = None

    def __init__(self, dc, map, scale, offset, region = None,
                 resolution = 72.0, honor_visibility = None):
        """Inititalize the renderer.

        dc -- the device context to render on.

        scale, offset -- the scale factor and translation to convert
                between projected coordinates and the DC coordinates

        region -- The region to draw as a (x, y, width, height) tuple in
                  the map's coordinate system. Default is None meaning
                  to draw everything.

        resolution -- the assumed resolution of the DC. Used to convert
                absolute lengths like font sizes to DC coordinates. The
                default is 72.0. If given, this parameter must be
                provided as a keyword argument.

        honor_visibility -- boolean. If true, honor the visibility flag
                of the layers, otherwise draw all layers. If None (the
                default), use the renderer's default. If given, this
                parameter must be provided as a keyword argument.
        """
        # resolution in pixel/inch
        self.dc = dc
        self.map = map
        self.scale = scale
        self.offset = offset
        self.region = region
        if honor_visibility is not None:
            self.honor_visibility = honor_visibility
        # store the resolution in pixel/point because it's more useful
        # later.
        self.resolution = resolution / 72.0

    def tools_for_property(self, prop):
        """Return a suitable pen and brush for the property

        This method must be implemented in derived classes. The return
        value should be a tuple (pen, brush).
        """
        raise NotImplementedError

    def render_map(self):
        """Render the map onto the DC.

        Both map and DC are the ones the renderer was instantiated with.

        This method is just a front-end for render_map_incrementally
        which does all rendering in one go. It also calls the dc's
        BeginDrawing and EndDrawing methods before and after calling
        render_map_incrementally.
        """

        self.dc.BeginDrawing()
        try:
            for cont in self.render_map_incrementally():
                pass
        finally:
            self.dc.EndDrawing()

    def render_map_incrementally(self):
        """Render the map incrementally.

        Return an iterator whose next method should be called until it
        returns False. After returning False it will raise StopIteration
        so that you could also use it in a for loop (implementation
        detail: this method is implemented as a generator).

        Iterate through all layers and draw them. Layers containing
        vector data are drawn with the draw_shape_layer method, raster
        layers are drawn with draw_raster_layer. The label layer is
        drawn last with draw_label_layer.

        During execution of this method, the map is bound to self.map so
        that methods especially in derived classes have access to the
        map if necessary.
        """
        # Whether the raster layer has already been drawn. See below for
        # the optimization this is used for
        seenRaster = True

        #
        # This is only a good optimization if there is only one
        # raster layer and the image covers the entire window (as
        # it currently does). We note if there is a raster layer
        # and only begin drawing layers once we have drawn it.
        # That way we avoid drawing layers that won't be seen.
        #
        if Thuban.Model.resource.has_gdal_support():
            for layer in self.map.Layers():
                if isinstance(layer, RasterLayer) and layer.Visible():
                    seenRaster = False
                    break

        for layer in self.map.Layers():
            # if honor_visibility is true, only draw visible layers,
            # otherwise draw all layers
            if not self.honor_visibility or layer.Visible():
                if isinstance(layer, Layer) and seenRaster:
                    for i in self.draw_shape_layer_incrementally(layer):
                        yield True
                elif isinstance(layer, RasterLayer) \
                    and Thuban.Model.resource.has_gdal_support():
                    self.draw_raster_layer(layer)
                    seenRaster = True
                    yield True
                else:
                    # look it up in the renderer extensions
                    for cls, func in _renderer_extensions:
                        if isinstance(layer, cls):
                            for i in func(self, layer):
                                yield True
                            break
                    else:
                        # No renderer found. Print a message about it
                        print >>sys.stderr, ("Drawing layer %r not supported"
                                             % layer)
            yield True

        self.draw_label_layer(self.map.LabelLayer())
        yield False

    def draw_shape_layer_incrementally(self, layer):
        """Draw the shape layer layer onto the map incrementally.

        This method is a generator which yields True after every 500
        shapes.
        """
        scale = self.scale
        offx, offy = self.offset

        map_proj = self.map.projection
        layer_proj = layer.projection

        brush = self.TRANSPARENT_BRUSH
        pen   = self.TRANSPARENT_PEN

        old_prop = None
        old_group = None
        lc = layer.GetClassification()
        field = layer.GetClassificationColumn()
        defaultGroup = lc.GetDefaultGroup()
        table = layer.ShapeStore().Table()

        if lc.GetNumGroups() == 0:
            # There's only the default group, so we can pretend that
            # there is no field to classifiy on which makes things
            # faster since we don't need the attribute information at
            # all.
            field = None

        # Determine which render function to use.
        useraw, draw_func, draw_func_param = self.low_level_renderer(layer)

        #
        # Iterate through all shapes that have to be drawn.
        #

        # Count the shapes drawn so that we can yield every few hundred
        # shapes
        count = 0

        # Cache the tools (pens and brushes) for the classification
        # groups. This is a mapping from the group's ids to the a tuple
        # (pen, brush)
        tool_cache = {}

        for shape in self.layer_shapes(layer):
            count += 1
            if field is None:
                group = defaultGroup
            else:
                value = table.ReadValue(shape.ShapeID(), field)
                group = lc.FindGroup(value)

            if not group.IsVisible():
                continue

            try:
                pen, brush = tool_cache[id(group)]
            except KeyError:
                pen, brush = tool_cache[id(group)] \
                             = self.tools_for_property(group.GetProperties())

            if useraw:
                data = shape.RawData()
            else:
                data = shape.Points()
            draw_func(draw_func_param, data, pen, brush)
            if count % 500 == 0:
                yield True

    def layer_shapes(self, layer):
        """Return an iterable over the shapes to be drawn from the given layer.

        The default implementation simply returns all ids in the layer.
        Override in derived classes to be more precise.
        """
        return layer.ShapeStore().AllShapes()

    def low_level_renderer(self, layer):
        """Return the low-level renderer for the layer for draw_shape_layer

        The low level renderer to be returned by this method is a tuple
        (useraw, func, param) where useraw is a boolean indicating
        whether the function uses the raw shape data, func is a callable
        object and param is passed as the first parameter to func. The
        draw_shape_layer method will call func like this:

            func(param, shapedata, pen, brush)

        where shapedata is the return value of the RawData method of the
        shape object if useraw is true or the return value of the Points
        method if it's false. pen and brush are the pen and brush to use
        to draw the shape on the dc.

        The default implementation returns one of
        self.draw_polygon_shape, self.draw_arc_shape or
        self.draw_point_shape as func and layer as param. None of the
        method use the raw shape data. Derived classes can override this
        method to return more efficient low level renderers.
        """
        shapetype = layer.ShapeType()
        if shapetype == SHAPETYPE_POINT:
            func = self.draw_point_shape
        elif shapetype == SHAPETYPE_ARC:
            func = self.draw_arc_shape
        else:
            func = self.draw_polygon_shape
        return False, func, layer

    def make_point(self, x, y):
        """Convert (x, y) to a point object.

        Derived classes must override this method.
        """
        raise NotImplementedError

    def projected_points(self, layer, points):
        """Return the projected coordinates of the points taken from layer.

        Transform all the points in the list of lists of coordinate
        pairs in points.

        The transformation applies the inverse of the layer's projection
        if any, then the map's projection if any and finally applies
        self.scale and self.offset.

        The returned list has the same structure as the one returned the
        shape's Points method.
        """
        proj = self.map.GetProjection()
        if proj is not None:
            forward = proj.Forward
        else:
            forward = None
        proj = layer.GetProjection()
        if proj is not None:
            inverse = proj.Inverse
        else:
            inverse = None
        result = []
        scale = self.scale
        offx, offy = self.offset
        make_point = self.make_point
        for part in points:
            result.append([])
            for x, y in part:
                if inverse:
                    x, y = inverse(x, y)
                if forward:
                    x, y = forward(x, y)
                result[-1].append(make_point(x * scale + offx,
                                             -y * scale + offy))
        return result

    def draw_polygon_shape(self, layer, points, pen, brush):
        """Draw a polygon shape from layer with the given brush and pen

        The shape is given by points argument which is a the return
        value of the shape's Points() method. The coordinates in the
        DC's coordinate system are determined with
        self.projected_points.
        """
        points = self.projected_points(layer, points)

        if brush is not self.TRANSPARENT_BRUSH:
            polygon = []
            for part in points:
                polygon.extend(part)

            insert_index = len(polygon)
            for part in points[:-1]:
                polygon.insert(insert_index, part[0])

            self.dc.SetBrush(brush)
            self.dc.SetPen(self.TRANSPARENT_PEN)
            self.dc.DrawPolygon(polygon)

        if pen is not self.TRANSPARENT_PEN:
            # At last draw the boundarys of the simple polygons
            self.dc.SetBrush(self.TRANSPARENT_BRUSH)
            self.dc.SetPen(pen)
            for part in points:
                self.dc.DrawLines(part)

    def draw_arc_shape(self, layer, points, pen, brush):
        """Draw an arc shape from layer with the given brush and pen

        The shape is given by points argument which is a the return
        value of the shape's Points() method. The coordinates in the
        DC's coordinate system are determined with
        self.projected_points.
        """
        points = self.projected_points(layer, points)
        self.dc.SetBrush(brush)
        self.dc.SetPen(pen)
        for part in points:
            self.dc.DrawLines(part)

    def draw_point_shape(self, layer, points, pen, brush):
        """Draw a point shape from layer with the given brush and pen

        The shape is given by points argument which is a the return
        value of the shape's Points() method. The coordinates in the
        DC's coordinate system are determined with
        self.projected_points.

        The point is drawn as a circle centered on the point.
        """
        points = self.projected_points(layer, points)
        if not points:
            return

        radius = self.resolution * 5
        self.dc.SetBrush(brush)
        self.dc.SetPen(pen)
        for part in points:
            for p in part:
                self.dc.DrawEllipse(p.x - radius, p.y - radius,
                                    2 * radius, 2 * radius)

    def draw_raster_layer(self, layer):
        """Draw the raster layer

        This implementation does the projection and scaling of the data
        as required by the layer's and map's projections and the scale
        and offset of the renderer and then hands the transformed data
        to self.draw_raster_data() which has to be implemented in
        derived classes.
        """
        offx, offy = self.offset
        width, height = self.dc.GetSizeTuple()

        in_proj = ""
        proj = layer.GetProjection()
        if proj is not None:
            for p in proj.GetAllParameters():
                in_proj += "+" + p + " "

        out_proj = ""
        proj = self.map.GetProjection()
        if proj is not None:
            for p in proj.GetAllParameters():
                out_proj += "+" + p + " "

        xmin = (0 - offx) / self.scale
        ymin = (offy - height) / self.scale
        xmax = (width - offx) / self.scale
        ymax = (offy - 0) / self.scale

        try:
            data = ProjectRasterFile(layer.GetImageFilename(),
                                     in_proj, out_proj,
                                     (xmin, ymin, xmax, ymax), "",
                                     (width, height))
        except (IOError, AttributeError, ValueError):
            # Why does this catch AttributeError and ValueError?
            # FIXME: The exception should be communicated to the user
            # better.
            traceback.print_exc()
        else:
            self.draw_raster_data(data, "BMP")

    def draw_raster_data(self, data, format="BMP"):
        """Draw the raster image in data onto the DC

        The raster image data is a string holding the data in the format
        indicated by the format parameter. The image is assumed to be
        exactly the size of the dc and to cover it completely.

        The format parameter is a string with the name of the format.
        The following format names should be used:

          'BMP' -- Windows Bitmap
          'JPEG' -- Jpeg

        The default format is 'bmp'.

        This method has to be implemented by derived classes. The
        implementation in the derived class should try to support at
        least the formats specified above and may support more.
        """
        raise NotImplementedError

    def label_font(self):
        """Return the font object for the label layer"""
        raise NotImplementedError

    def draw_label_layer(self, layer):
        """Draw the label layer

        All labels are draw in the font returned by self.label_font().
        """
        scale = self.scale
        offx, offy = self.offset

        self.dc.SetFont(self.label_font())

        map_proj = self.map.projection
        if map_proj is not None:
            forward = map_proj.Forward
        else:
            forward = None

        for label in layer.Labels():
            x = label.x
            y = label.y
            text = label.text
            if forward:
                x, y = forward(x, y)
            x = x * scale + offx
            y = -y * scale + offy
            width, height = self.dc.GetTextExtent(text)
            if label.halign == ALIGN_LEFT:
                # nothing to be done
                pass
            elif label.halign == ALIGN_RIGHT:
                x = x - width
            elif label.halign == ALIGN_CENTER:
                x = x - width/2
            if label.valign == ALIGN_TOP:
                # nothing to be done
                pass
            elif label.valign == ALIGN_BOTTOM:
                y = y - height
            elif label.valign == ALIGN_CENTER:
                y = y - height/2
            self.dc.DrawText(text, x, y)
1	# Copyright (c) 2001, 2002, 2003 by Intevation GmbH
2	# Authors:
3	# Bernhard Herzog <[email protected]>
4	# Jonathan Coles <[email protected]>
5	# Frank Koormann <[email protected]>
6	#
7	# This program is free software under the GPL (>=v2)
8	# Read the file COPYING coming with Thuban for details.
9
10	"""Basic rendering logic for Thuban maps
11
12	The code in this module is completely independend of wx so that it can
13	be tested reasonably easily and it could make it easier to write non-wx
14	renderers.
15	"""
16
17	from __future__ import generators
18
19	__version__ = "$Revision$"
20	# $Source$
21	# $Id$
22
23	import sys
24	import traceback
25
26	from Thuban.Model.layer import Layer, RasterLayer
27	from Thuban.Model.data import SHAPETYPE_ARC, SHAPETYPE_POINT
28	from Thuban.Model.label import ALIGN_CENTER, ALIGN_TOP, ALIGN_BOTTOM, \
29	ALIGN_LEFT, ALIGN_RIGHT
30
31	import Thuban.Model.resource
32
33	if Thuban.Model.resource.has_gdal_support():
34	from gdalwarp import ProjectRasterFile
35
36
37	#
38	# Renderer Extensions
39	#
40	# The renderer extensions provide a way to render layer types defined in
41	# Thuban extensions. The renderer extensions are stored as a list with
42	# (layer_class, draw_function) pairs. If the renderer has to draw a
43	# non-builtin layer type, i.e. a layer that is not a subclass of Layer
44	# or RasterLayer, it iterates through that list, tests whether the layer
45	# to be drawin is an instance of layer_class and if so calls
46	# draw_function with the renderer and the layer as arguments. Since
47	# drawing is done incrementally, the draw_function should return an
48	# iterable. The easiest way is to simply implement the draw_function as
49	# a generator and to yield in suitable places, or to return the empty
50	# tuple.
51	#
52	# New renderer extensions should be added with add_renderer_extension().
53	# If necessary the extensions list can be reset with
54	# init_renderer_extensions().
55
56	_renderer_extensions = []
57
58	def add_renderer_extension(layer_class, function):
59	"""Add a renderer extension for the layer class layer_class
60
61	When an instance of layer_class is to be drawn by the renderer the
62	renderer will call function with the renderer and the layer_class
63	instance as arguments. Since drawing is done incrementally, the
64	function should return an iterable. The easiest way is to simply
65	implement the draw_function as a generator and to yield True in
66	suitable places, or to return the empty tuple if it's not possible
67	to do the rendering in incrementally.
68	"""
69	_renderer_extensions.append((layer_class, function))
70
71	def init_renderer_extensions():
72	"""(Re)initialize the list of renderer extensions
73
74	Calling this function outside of the test suite is probably not
75	useful.
76	"""
77	del _renderer_extensions[:]
78
79
80	#
81	# Base Renderer
82	#
83
84	class BaseRenderer:
85
86	"""Basic Renderer Infrastructure for Thuban Maps
87
88	This class can't be used directly to render because it doesn't know
89	anything about real DCs such as how to create pens or brushes. That
90	functionality has to be provided by derived classes. The reason for
91	this is that it makes the BaseRenderer completely independend of wx
92	and thus it's quite easy to write test cases for it.
93	"""
94	# If true the render honors the visibility flag of the layers
95	honor_visibility = 1
96
97	# Transparent brushes and pens. Derived classes should define these
98	# as appropriate.
99	TRANSPARENT_PEN = None
100	TRANSPARENT_BRUSH = None
101
102	def __init__(self, dc, map, scale, offset, region = None,
103	resolution = 72.0, honor_visibility = None):
104	"""Inititalize the renderer.
105
106	dc -- the device context to render on.
107
108	scale, offset -- the scale factor and translation to convert
109	between projected coordinates and the DC coordinates
110
111	region -- The region to draw as a (x, y, width, height) tuple in
112	the map's coordinate system. Default is None meaning
113	to draw everything.
114
115	resolution -- the assumed resolution of the DC. Used to convert
116	absolute lengths like font sizes to DC coordinates. The
117	default is 72.0. If given, this parameter must be
118	provided as a keyword argument.
119
120	honor_visibility -- boolean. If true, honor the visibility flag
121	of the layers, otherwise draw all layers. If None (the
122	default), use the renderer's default. If given, this
123	parameter must be provided as a keyword argument.
124	"""
125	# resolution in pixel/inch
126	self.dc = dc
127	self.map = map
128	self.scale = scale
129	self.offset = offset
130	self.region = region
131	if honor_visibility is not None:
132	self.honor_visibility = honor_visibility
133	# store the resolution in pixel/point because it's more useful
134	# later.
135	self.resolution = resolution / 72.0
136
137	def tools_for_property(self, prop):
138	"""Return a suitable pen and brush for the property
139
140	This method must be implemented in derived classes. The return
141	value should be a tuple (pen, brush).
142	"""
143	raise NotImplementedError
144
145	def render_map(self):
146	"""Render the map onto the DC.
147
148	Both map and DC are the ones the renderer was instantiated with.
149
150	This method is just a front-end for render_map_incrementally
151	which does all rendering in one go. It also calls the dc's
152	BeginDrawing and EndDrawing methods before and after calling
153	render_map_incrementally.
154	"""
155
156	self.dc.BeginDrawing()
157	try:
158	for cont in self.render_map_incrementally():
159	pass
160	finally:
161	self.dc.EndDrawing()
162
163	def render_map_incrementally(self):
164	"""Render the map incrementally.
165
166	Return an iterator whose next method should be called until it
167	returns False. After returning False it will raise StopIteration
168	so that you could also use it in a for loop (implementation
169	detail: this method is implemented as a generator).
170
171	Iterate through all layers and draw them. Layers containing
172	vector data are drawn with the draw_shape_layer method, raster
173	layers are drawn with draw_raster_layer. The label layer is
174	drawn last with draw_label_layer.
175
176	During execution of this method, the map is bound to self.map so
177	that methods especially in derived classes have access to the
178	map if necessary.
179	"""
180	# Whether the raster layer has already been drawn. See below for
181	# the optimization this is used for
182	seenRaster = True
183
184	#
185	# This is only a good optimization if there is only one
186	# raster layer and the image covers the entire window (as
187	# it currently does). We note if there is a raster layer
188	# and only begin drawing layers once we have drawn it.
189	# That way we avoid drawing layers that won't be seen.
190	#
191	if Thuban.Model.resource.has_gdal_support():
192	for layer in self.map.Layers():
193	if isinstance(layer, RasterLayer) and layer.Visible():
194	seenRaster = False
195	break
196
197	for layer in self.map.Layers():
198	# if honor_visibility is true, only draw visible layers,
199	# otherwise draw all layers
200	if not self.honor_visibility or layer.Visible():
201	if isinstance(layer, Layer) and seenRaster:
202	for i in self.draw_shape_layer_incrementally(layer):
203	yield True
204	elif isinstance(layer, RasterLayer) \
205	and Thuban.Model.resource.has_gdal_support():
206	self.draw_raster_layer(layer)
207	seenRaster = True
208	yield True
209	else:
210	# look it up in the renderer extensions
211	for cls, func in _renderer_extensions:
212	if isinstance(layer, cls):
213	for i in func(self, layer):
214	yield True
215	break
216	else:
217	# No renderer found. Print a message about it
218	print >>sys.stderr, ("Drawing layer %r not supported"
219	% layer)
220	yield True
221
222	self.draw_label_layer(self.map.LabelLayer())
223	yield False
224
225	def draw_shape_layer_incrementally(self, layer):
226	"""Draw the shape layer layer onto the map incrementally.
227
228	This method is a generator which yields True after every 500
229	shapes.
230	"""
231	scale = self.scale
232	offx, offy = self.offset
233
234	map_proj = self.map.projection
235	layer_proj = layer.projection
236
237	brush = self.TRANSPARENT_BRUSH
238	pen = self.TRANSPARENT_PEN
239
240	old_prop = None
241	old_group = None
242	lc = layer.GetClassification()
243	field = layer.GetClassificationColumn()
244	defaultGroup = lc.GetDefaultGroup()
245	table = layer.ShapeStore().Table()
246
247	if lc.GetNumGroups() == 0:
248	# There's only the default group, so we can pretend that
249	# there is no field to classifiy on which makes things
250	# faster since we don't need the attribute information at
251	# all.
252	field = None
253
254	# Determine which render function to use.
255	useraw, draw_func, draw_func_param = self.low_level_renderer(layer)
256
257	#
258	# Iterate through all shapes that have to be drawn.
259	#
260
261	# Count the shapes drawn so that we can yield every few hundred
262	# shapes
263	count = 0
264
265	# Cache the tools (pens and brushes) for the classification
266	# groups. This is a mapping from the group's ids to the a tuple
267	# (pen, brush)
268	tool_cache = {}
269
270	for shape in self.layer_shapes(layer):
271	count += 1
272	if field is None:
273	group = defaultGroup
274	else:
275	value = table.ReadValue(shape.ShapeID(), field)
276	group = lc.FindGroup(value)
277
278	if not group.IsVisible():
279	continue
280
281	try:
282	pen, brush = tool_cache[id(group)]
283	except KeyError:
284	pen, brush = tool_cache[id(group)] \
285	= self.tools_for_property(group.GetProperties())
286
287	if useraw:
288	data = shape.RawData()
289	else:
290	data = shape.Points()
291	draw_func(draw_func_param, data, pen, brush)
292	if count % 500 == 0:
293	yield True
294
295	def layer_shapes(self, layer):
296	"""Return an iterable over the shapes to be drawn from the given layer.
297
298	The default implementation simply returns all ids in the layer.
299	Override in derived classes to be more precise.
300	"""
301	return layer.ShapeStore().AllShapes()
302
303	def low_level_renderer(self, layer):
304	"""Return the low-level renderer for the layer for draw_shape_layer
305
306	The low level renderer to be returned by this method is a tuple
307	(useraw, func, param) where useraw is a boolean indicating
308	whether the function uses the raw shape data, func is a callable
309	object and param is passed as the first parameter to func. The
310	draw_shape_layer method will call func like this:
311
312	func(param, shapedata, pen, brush)
313
314	where shapedata is the return value of the RawData method of the
315	shape object if useraw is true or the return value of the Points
316	method if it's false. pen and brush are the pen and brush to use
317	to draw the shape on the dc.
318
319	The default implementation returns one of
320	self.draw_polygon_shape, self.draw_arc_shape or
321	self.draw_point_shape as func and layer as param. None of the
322	method use the raw shape data. Derived classes can override this
323	method to return more efficient low level renderers.
324	"""
325	shapetype = layer.ShapeType()
326	if shapetype == SHAPETYPE_POINT:
327	func = self.draw_point_shape
328	elif shapetype == SHAPETYPE_ARC:
329	func = self.draw_arc_shape
330	else:
331	func = self.draw_polygon_shape
332	return False, func, layer
333
334	def make_point(self, x, y):
335	"""Convert (x, y) to a point object.
336
337	Derived classes must override this method.
338	"""
339	raise NotImplementedError
340
341	def projected_points(self, layer, points):
342	"""Return the projected coordinates of the points taken from layer.
343
344	Transform all the points in the list of lists of coordinate
345	pairs in points.
346
347	The transformation applies the inverse of the layer's projection
348	if any, then the map's projection if any and finally applies
349	self.scale and self.offset.
350
351	The returned list has the same structure as the one returned the
352	shape's Points method.
353	"""
354	proj = self.map.GetProjection()
355	if proj is not None:
356	forward = proj.Forward
357	else:
358	forward = None
359	proj = layer.GetProjection()
360	if proj is not None:
361	inverse = proj.Inverse
362	else:
363	inverse = None
364	result = []
365	scale = self.scale
366	offx, offy = self.offset
367	make_point = self.make_point
368	for part in points:
369	result.append([])
370	for x, y in part:
371	if inverse:
372	x, y = inverse(x, y)
373	if forward:
374	x, y = forward(x, y)
375	result[-1].append(make_point(x * scale + offx,
376	-y * scale + offy))
377	return result
378
379	def draw_polygon_shape(self, layer, points, pen, brush):
380	"""Draw a polygon shape from layer with the given brush and pen
381
382	The shape is given by points argument which is a the return
383	value of the shape's Points() method. The coordinates in the
384	DC's coordinate system are determined with
385	self.projected_points.
386	"""
387	points = self.projected_points(layer, points)
388
389	if brush is not self.TRANSPARENT_BRUSH:
390	polygon = []
391	for part in points:
392	polygon.extend(part)
393
394	insert_index = len(polygon)
395	for part in points[:-1]:
396	polygon.insert(insert_index, part[0])
397
398	self.dc.SetBrush(brush)
399	self.dc.SetPen(self.TRANSPARENT_PEN)
400	self.dc.DrawPolygon(polygon)
401
402	if pen is not self.TRANSPARENT_PEN:
403	# At last draw the boundarys of the simple polygons
404	self.dc.SetBrush(self.TRANSPARENT_BRUSH)
405	self.dc.SetPen(pen)
406	for part in points:
407	self.dc.DrawLines(part)
408
409	def draw_arc_shape(self, layer, points, pen, brush):
410	"""Draw an arc shape from layer with the given brush and pen
411
412	The shape is given by points argument which is a the return
413	value of the shape's Points() method. The coordinates in the
414	DC's coordinate system are determined with
415	self.projected_points.
416	"""
417	points = self.projected_points(layer, points)
418	self.dc.SetBrush(brush)
419	self.dc.SetPen(pen)
420	for part in points:
421	self.dc.DrawLines(part)
422
423	def draw_point_shape(self, layer, points, pen, brush):
424	"""Draw a point shape from layer with the given brush and pen
425
426	The shape is given by points argument which is a the return
427	value of the shape's Points() method. The coordinates in the
428	DC's coordinate system are determined with
429	self.projected_points.
430
431	The point is drawn as a circle centered on the point.
432	"""
433	points = self.projected_points(layer, points)
434	if not points:
435	return
436
437	radius = self.resolution * 5
438	self.dc.SetBrush(brush)
439	self.dc.SetPen(pen)
440	for part in points:
441	for p in part:
442	self.dc.DrawEllipse(p.x - radius, p.y - radius,
443	2 * radius, 2 * radius)
444
445	def draw_raster_layer(self, layer):
446	"""Draw the raster layer
447
448	This implementation does the projection and scaling of the data
449	as required by the layer's and map's projections and the scale
450	and offset of the renderer and then hands the transformed data
451	to self.draw_raster_data() which has to be implemented in
452	derived classes.
453	"""
454	offx, offy = self.offset
455	width, height = self.dc.GetSizeTuple()
456
457	in_proj = ""
458	proj = layer.GetProjection()
459	if proj is not None:
460	for p in proj.GetAllParameters():
461	in_proj += "+" + p + " "
462
463	out_proj = ""
464	proj = self.map.GetProjection()
465	if proj is not None:
466	for p in proj.GetAllParameters():
467	out_proj += "+" + p + " "
468
469	xmin = (0 - offx) / self.scale
470	ymin = (offy - height) / self.scale
471	xmax = (width - offx) / self.scale
472	ymax = (offy - 0) / self.scale
473
474	try:
475	data = ProjectRasterFile(layer.GetImageFilename(),
476	in_proj, out_proj,
477	(xmin, ymin, xmax, ymax), "",
478	(width, height))
479	except (IOError, AttributeError, ValueError):
480	# Why does this catch AttributeError and ValueError?
481	# FIXME: The exception should be communicated to the user
482	# better.
483	traceback.print_exc()
484	else:
485	self.draw_raster_data(data, "BMP")
486
487	def draw_raster_data(self, data, format="BMP"):
488	"""Draw the raster image in data onto the DC
489
490	The raster image data is a string holding the data in the format
491	indicated by the format parameter. The image is assumed to be
492	exactly the size of the dc and to cover it completely.
493
494	The format parameter is a string with the name of the format.
495	The following format names should be used:
496
497	'BMP' -- Windows Bitmap
498	'JPEG' -- Jpeg
499
500	The default format is 'bmp'.
501
502	This method has to be implemented by derived classes. The
503	implementation in the derived class should try to support at
504	least the formats specified above and may support more.
505	"""
506	raise NotImplementedError
507
508	def label_font(self):
509	"""Return the font object for the label layer"""
510	raise NotImplementedError
511
512	def draw_label_layer(self, layer):
513	"""Draw the label layer
514
515	All labels are draw in the font returned by self.label_font().
516	"""
517	scale = self.scale
518	offx, offy = self.offset
519
520	self.dc.SetFont(self.label_font())
521
522	map_proj = self.map.projection
523	if map_proj is not None:
524	forward = map_proj.Forward
525	else:
526	forward = None
527
528	for label in layer.Labels():
529	x = label.x
530	y = label.y
531	text = label.text
532	if forward:
533	x, y = forward(x, y)
534	x = x * scale + offx
535	y = -y * scale + offy
536	width, height = self.dc.GetTextExtent(text)
537	if label.halign == ALIGN_LEFT:
538	# nothing to be done
539	pass
540	elif label.halign == ALIGN_RIGHT:
541	x = x - width
542	elif label.halign == ALIGN_CENTER:
543	x = x - width/2
544	if label.valign == ALIGN_TOP:
545	# nothing to be done
546	pass
547	elif label.valign == ALIGN_BOTTOM:
548	y = y - height
549	elif label.valign == ALIGN_CENTER:
550	y = y - height/2
551	self.dc.DrawText(text, x, y)
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